This invention relates to compositions and methods for conditioning fabrics during the rinse cycle of home laundering operations. This is a widely used practice to impart to laundered fabrics a texture or handle that is smooth, pliable and fluffy to the touch (i.e. soft) and also to impart to the fabrics a reduced tendency to pick up and/or retain an electrostatic charge (i.e. static control), especially when the fabrics are dried in an automatic dryer.
It has become commonplace today for homemakers to use fabric conditioning compositions comprising major amounts of water, lesser amounts of fabric conditioning agents, and minor amounts of optional ingredients such as perfumes, colorants, preservatives and stabilizers. Such compositions are aqueous suspensions or emulsions which can be conveniently added to the rinsing bath of home laundry operations.
Many compounds have been disclosed as having the capacity to condition fabrics. One common class is cationic in nature. A representative disclosure of cationic fabric conditioning agents appears in column 2 of U.S. Pat. No. 3,756,950 issued to Gluck on Sept. 4, 1973. The use of alkyl amido imidazolinium salts as fabric conditioning agents in liquid compositions is disclosed in U.S. Pat. No. 3,904,533 issued to Neiditch on Sept. 9, 1975. The use of polyamido quaternized biurets as cationic fabric conditioners is disclosed by Okamato et al, Japanese patent publication 42-15596 published Aug. 28, 1967. The foregoing Gluck, Neiditch and Okamato reference are herein incorporated by reference.
A number of prior art compositions, both as disclosed in the literature and as sold commercially, contain minor amounts of solvents to improve stability and/or control viscosity. For example, U.S. Pat. Nos. 3,954,634 granted on May 4, 1976 to Monson et al and 3,729,416 granted on Apr. 24, 1973 to Bruning et al, the latter mentioning alkanols, alkanediols, alkoxyalkane diols, and alkanones.
Katsumi et al, U.S. Pat. No. 3,850,818 issued Nov. 26, 1974 discloses certain ethoxylated quaternary salts as fabric conditioning agents, admixed in specified proportions with conventional quaternaries and with one or more of the following additives: C.sub.1-3 alcohols, glycols, glycerol, sorbitol and urea. Katsumi's ethoxylated quaternaries have the structure ##STR1## where R.sub.1 is long chain alkyl; R.sub.2 is benzyl or an alkyl group having from 1 to 3 carbon atoms; the sum (m + n) is from 20 to 100; and X is Cl, Br or C.sub.2 H.sub.5 SO.sub.4.
Renold, U.S. Pat. No. 3,879,300 issued Apr. 22, 1975 discloses as a fabric softener the compound N-higher alkyl-1,3 propylene diamine, and formulates it into compositions containing urea or sugar as an additive to improve softening or color. Glycols and alcohols may also be used.
Another means that has been suggested for the preparation of physically stable liquid fabric conditioning compositions is homogenization, as for example by Monson et al in U.S. Pat. No. 3,729,416 cited hereinbefore.
Among the objects of the present invention are the preparation of physically stable compositions providing good fabric softening and fabric antistatic properties, produced economically without the need for homogenization, and formulated from relatively low cost and commercially available raw materials without the need for expensive and potentially hazardous solvents.